Fractures of the radial head account for two to five percent of all adult fractures and are typically treated with a variety of surgical and non-surgical options depending upon the severity of the injury. For example, surgical options for more severe injuries to the radial head can include open reduction with internal fixation (ORIF), radial head resection, hemi-arthroplasty of the radial head, and total elbow replacement. Hemi-arthroplasty of the radial head involves resecting the fractured and damaged radial head and replacing the natural articulation with an artificial one by use of an implant. The implant articulates with the natural cartilage surface of the capitulum of the distal humerus. Over time, radial head implant apparatuses and methods utilized for treatment have evolved to continuously improve surgical outcomes.
As can be appreciated by those of skill in the art, indications which can be associated with the use of radial head implant apparatuses and methods can include:                Comminuted radial fracture with or with associated elbow instability;        Comminuted radial fracture with associated rupture of the interosseous membrane, the Essex-Lopresti lesion;        Post-traumatic arthritis involving the radiocapitellar or proximal radioulnar joint;        Primary osteoarthritis involving the radiocapitellar joint or proximal radioulnar joint;        Rheumatoid arthritis involving the radiocapitellar joint or proximal radioulnar joint; and        Revision of a failed radial head prosthesis.        
It is well known that a number of factors typically have a significant impact on the clinical outcome of a radial head implant. Four such factors, for example, are: biocompatibility of the implant; implant stiffness, which should be sufficient to prevent joint collapse under physiological loading; ability of the implant to restore correct head height and tissue balance and prevent gross changes in joint kinematics (i.e., a valgus laxity); and ability of the implant to minimize stress placed upon the capitellar articulation. It is therefore desirable for a radial head apparatus to be biocompatible, sufficiently stiff, allow for enough surgical flexibility to restore natural joint kinematics despite anatomical variations, and minimize the stress placed upon surrounding tissues.